1. Field
The present disclosure relates to wireless communication systems, and more particularly, to white space (WS) techniques in Long Term Evolution (LTE) systems.
2. Background
Wireless communication systems are widely deployed to provide various types of communication content such as voice, data, video and the like, and deployments are likely to increase with introduction of new data oriented systems, such as Long Term Evolution (LTE) systems. Wireless communications systems may be multiple-access systems capable of supporting communication with multiple users by sharing the available system resources (e.g., bandwidth and transmit power). Examples of such multiple-access systems include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, 3GPP LTE systems and other orthogonal frequency division multiple access (OFDMA) systems.
3GPP LTE represents a major advance in cellular technology as an evolution of Global System for Mobile communications (GSM) and Universal Mobile Telecommunications System (UMTS). The LTE physical layer (PHY) provides a highly efficient way to convey both data and control information between base stations, such as an evolved Node Bs (eNBs), and mobile entities.
An orthogonal frequency division multiplex (OFDM) communication system effectively partitions the overall system bandwidth into multiple (NF) subcarriers, which may also be referred to as frequency sub-channels, tones, or frequency bins. For an OFDM system, the data to be transmitted (i.e., the information bits) is first encoded with a particular coding scheme to generate coded bits, and the coded bits are further grouped into multi-bit symbols that are then mapped to modulation symbols. Each modulation symbol corresponds to a point in a signal constellation defined by a particular modulation scheme (e.g., M-PSK or M-QAM) used for data transmission. At each time interval that may be dependent on the bandwidth of each frequency subcarrier, a modulation symbol may be transmitted on each of the NF frequency subcarrier. Thus, OFDM may be used to combat inter-symbol interference (ISI) caused by frequency selective fading, which is characterized by different amounts of attenuation across the system bandwidth.
Generally, a wireless multiple-access communication system can simultaneously support communication for a number of mobile entities, such as, for example, user equipments (UEs) or access terminals (ATs). A UE may communicate with a base station via the downlink and uplink. The downlink (or forward link) refers to the communication link from the base station to the UE, and the uplink (or reverse link) refers to the communication link from the UE to the base station. Such communication links may be established via a single-in-single-out, multiple-in-signal-out, or a multiple-in-multiple-out (MIMO) system.
As the number of entities deployed increases, the need for proper bandwidth utilization on licensed as well as RF spectrum for which the cellular operator is not licensed or holds only a secondary license, including whitespace spectrum, becomes more important. In the context of cognitive radio networks, certain frequency bands may be underutilized by an incumbent primary licensee. Such frequency bands may be made available to secondary users (e.g. cellular operators) when the primary user is not active. Due to changes in primary and/or secondary user activity, changing the operating spectrum for the secondary licensees may be necessary. In this context, there remains a need for efficient authentication and authorization of wireless devices serviced by cellular operators in cognitive LTE networks and/or similar wireless communication networks.